1. Field of the Invention
The present invention generally relates to a memory device, and more specifically, to a hybrid switch cell embodied as a cross-point cell using a nonvolatile ferroelectric capacitor and a hybrid switch, and a nonvolatile memory device using the hybrid switch cell to improve the whole size.
2. Description of the Prior Art
Generally, a ferroelectric random access memory (hereinafter, referred to as ‘FeRAM’) has attracted considerable attention as next generation memory device because it has a data processing speed as fast as a Dynamic Random Access Memory DRAM and conserves data even after the power is turned off.
The FeRAM having structures similar to the DRAM includes the capacitors made of a ferroelectric substance, so that it utilizes the characteristic of a high residual polarization of the ferroelectric substance in which data is not deleted even after an electric field is eliminated.
The technical contents on the above FeRAM are disclosed in the Korean Patent Application No. 2001-57275 by the same inventor of the present invention. Therefore, the basic structure and the operation on the FeRAM are not described herein.
The conventional FeRAM device comprises a switching device which is switched depending on a voltage of a word line and connects a nonvolatile ferroelectric capacitor to a sub bit line. The nonvolatile ferroelectric capacitor is connected to a terminal of the switching device and a plate line.
Meanwhile, in the conventional FeRAM, a NMOS transistor whose switching operation is controlled by a gate control signal is used as the switching device.
However, the above-described NMOS transistor requires an additional area for gate control when a cell array is embodied with a switching device, which results in increase of the whole chip size.